The US stock market faces the test of the Supreme Court's ruling on the legality of tariffs

The US Supreme Court is poised to rule on the legality of Mr. Trump's sweeping tariffs introduced in April, in what could be the next test for a stock market that has been riding high for a while, sending global markets tumbling. The S & P 500, which has rallied 39 per cent since its low for the month, closed at a record high on Thursday, in part because the tariffs ended up being lower than Mr. Trump had threatened, buoyed by an artificial intelligence investment boom and continued high US economic growth. If the US Supreme Court rules that Mr. Trump has overstepped its authority with sweeping tariffs, there is still a lot of uncertainty ahead. A ruling is increasingly unlikely this year. The court held its last public hearing of the year on Wednesday, and the next hearing will not be held until January 9 next year. Ohsung Kwon, chief equity strategist at Wells Fargo, estimated in October that if the tariffs are invalidated, S & P 500 companies' earnings before interest and taxes will rise 2.4% by 2026 from this year's level.